Most rainwater and graywater systems are regulated by local, state and sometimes federal public health and safety legislation. The concern is to prevent contamination of public water supplies from individual installations that may not be properly designed, professionally installed or maintained. For example, imagine that you have municipally treated water service to your home and you install your own rainwater irrigation (non-potable) system and tie it to the municipal water piping (to use the municipal water as a backup for periods when it hasn’t rained in a while and you have exhausted your stores). If there is a fire down the road from your house and the fire truck starts pumping enough water out of the fire hydrant to cause low pressure on your supply line, without a backflow prevention valve your stored rainwater might be pulled into the public water lines. Even though you never intended for your rainwater to be used as potable water, it has now been sent out to an unknown number of your neighbors who will unknowingly drink it and may become ill. This is just one of many real world scenarios that we as responsible people must avoid. So it is important that these systems be installed by a licensed professional who complies with all safety regulations.
Rainwater systems for irrigation purposes typically consist of a gutter and downspout system installed on the edge of your roofline, and a series of underground pipes that take the captured water to one or more storage tanks. Purple plumbing pipe is used for these systems to indicate that they do not carry drinking water. It is important to have a professional rainwater system installer adjust the gutter pitch or angle in order to direct the water flow toward the downspouts, so it doesn’t back up, overflow and lose precious water. It is important, as well, to provide some kind of leaf guard or at least be vigilant in keeping leaf debris build up in the gutters to a minimum, as this can seriously impede water flow and cause water losses. Some people like to install some kind of leaf guard over the downspout intakes, to remove large debris that might get washed off the roof.
If you are using rainwater for drinking (potable) water, it’s also advisable to install a “first flush” tank to divert the first 50 or 100 gallons of water that carry dust, pollen and other loose water-soluble debris to a separation tank that keeps those contaminants out of your main tank. Unless your storage tank is elevated, you will need some kind of pump to get water back out of the tank and provide pressure for various uses. Typical treatment requirements for potable rainwater include a series of filters that remove sediments, contaminants and kill pathogens.
Although we have heard of household chlorine treatment systems, we believe it is important that we purify our water onsite with non- chemical methods. This usually consists of a sediment filter, an activated carbon filter and ultraviolet (UV) light. For whole-house water use, typically a larger pump is required that will provide enough pressure to pull the water from the storage tank and push it through the home’s plumbing. A pressure-regulating device should be installed to prevent damage to the home’s plumbing system.
Using water efficiently is important to assure that the rainwater captured makes a worthwhile contribution to your needs. A graywater system improves efficiency by reusing water from tubs and shower, bathroom lavatories and laundry for flushing toilets and outdoor landscape irrigation. This system requires separate plumbing drain lines from these locations to an external distribution tank dedicated for graywater. Again, purple plumbing pipes are used to indicate that they do not carry drinking water. You should also check your local and state regulations on how long this water can be stored and how it must be treated before it can be used or discharged.
Note that you cannot use graywater for edible landscapes or vegetable gardens. You also cannot use water from toilets, as this is considered blackwater, not graywater, and must be processed through some type of septic system. Blackwater often contains pathogens and disease organisms that could cause death or extreme illness. Some regulatory agencies also include wastewater from kitchen sinks or tubs and showers in the blackwater category. Depending on where you live, if you do not have access to a community sewer line you may need to manage sewer waste onsite. Septic systems vary in complexity and cost, so check local, county and state regulations to see what type of system is required for your location. Sometimes the type of system is dictated by the amount of land you have or the type of soil, so smaller parcels or areas with shallow clay soils may require more complex and expensive systems. This is to minimize the potential for your waste to spread disease to your neighbors or the public waterways and water supply. Composting toilets may be an option; again, check for any regulations that apply. Human waste is a valuable fertilizer resource in much of the world, but it often contains pathogens that can be lethal. Using composted human waste on food crops is a controversial subject due to concerns that improper treatment won’t kill viruses and other pathogens, as well as concerns for pharmaceutical residues.
Several US wastewater treatment facilities are using human waste to create soil amendments and fertilizers, after composting it to very high temperatures several times and then having it lab tested. Even then, they recommend that this sewer waste fertilizer not be used on gardens or crops meant for human consumption. Never use human waste by-products unless you are certain that they have been properly treated and are free from all potentially harmful pathogens.
